FIG. 1 illustrates a structure of an LTE mobile communication system.
Referring to FIG. 1, a wireless access network of the LTE mobile communication system includes a next-generation base station (Evolved Node B, EUTRAN, hereinafter, referred to as “eNB” or “NodeB”) 110, an MME (Mobility Management Entity) 120, and an S-GW (Serving-Gateway) 130. A user equipment (hereinafter, referred to as “terminal” or “UE”) 100 is connected to an external network via the eNB 110, the S-GW 130, and a P-GW (Packet Data Network-Gateway) 160. An AP (Application Function) is a device that exchanges application-related information with a user in the application level. A PCRF (Policy and Charging Rules Function) 150 is a device that controls a policy related to the Quality of Service (QoS) of a user, and a PCC (Policy and Charging Control) rule corresponding to the policy is transferred and applied to the P-GW 160.
The eNB 110 is an RAN (Radio Access Network) node, and corresponds to an RNC (Radio Network Controller) of a UTRAN system and a BSC (Base Station Controller) of a GERAN system. The eNB 110 is connected to the UE 100 via a wireless channel, and performs a similar role to the existing RNC/BSC.
In the LTE system, since all user traffic including a real-time service such as VoIP (Voice over IP) through an Internet protocol (IP) are serviced through a shared channel, a device for collecting and scheduling status information of UEs 100 is needed, and the eNB 110 serves as this device.
The S-GW 130 is an entity to provide data bearers and establishes and releases data bearers under the control of the MME 150. The MME 150 is responsible for various control functions and is connected to a plurality of eNBs.
The PCRF 150 is an entity that generally controls QoS and charging for traffic.
In general, a User Plane (UP) refers to a path connecting the UE 100 to the RAN node, the RAN node to the S-GW 130, and the S-GW 130 to the P-GW 160, through which user data is transmitted and/or received. Of this path, a section that uses a wireless channel with seriously limited resources is a path between the UE 100 and the RAN node.
In a wireless communication system such as LTE, QoS may be applied in units of EPS bearers. One EPS bearer is used to transport IP flows having the same QoS requirements. In the EPS bearers, QoS-related parameters may be designated and include QoS Class Identifier (QCI) and Allocation and Retention Priority (ARP). The EPS bearer corresponds to a PDP context of the GPRS system.
Therefore, there is a need for a method for reducing congestion that may occur due to limitations of resources in a wireless communication system.